EPIDEM

• Epidemiology


  Study the occurrence and distribution of diseases as well as distribution of determinants of health state or events in specified population and the application of this study to control health problems
• 1. E. A. Winslow: '“the diagnostic discipline of public health.”'
• Epidemic


  An increase in the frequency (incidence) of a disease above the usual and expected rate, which is called the endemic rate. Epidemiology counts cases of a disease and when they detect the sign of an epidemic, they ask who, when, and where questions
• Notifiable disease


  Any disease that is required by law to be reported to government authorities
• The ultimate goal of Epidemiology is to use knowledge to control and prevent the spread of disease
• John Snow: 'father of modern epidemiology, studied cholera'
• Two Main Areas of Investigation


  1. Describes the distribution of health status in terms of age, gender, race, geography, and time

  2. Patterns of disease distribution in terms of causal factors
• Uses of Epidemiology

  • Study the history of the health population and the rise and fall of diseases and changes in their character
  • Diagnose the health of the community and the condition of the people
  • Study the work of health services with a view of improving them
  • Estimate the risk of diseases, accidents, detects and the changes avoiding them
  • Complete the clinical feature of chronic disease and describe their natural history
  • Search for cause of health and disease
• Types of Agent

  • Living or non-living things, physical or mechanical in nature such as extremes of temperature, light electricity
  • Chemicals- endogenous (within the body) or exogenous (poison)
• Characteristics of Agent of Disease

  • Inherent characteristics
  • Characteristic in relation to the environment
  • Characteristic directly related to man: Infectivity, Pathogenicity, Virulence, Antigenicity
• Modes of Transmission


  • Direct Transmission
  • Airborne
  • Indirect Transmission: Vehicle borne, Vector-borne, Mechanical vector, Biological vector, Droplet nuclei, Dust
• Host Factor of Disease

  • Humoral defense - cells in our body like plasma cells and lymphocytes that produce antibodies to neutralize harmful effects of infectious agents and body fluids in our body that possess substances that have antimicrobial properties
  • Cellular defense - cells in our body like macrophages and neutrophils involved in the process of phagocytosis
• Factors affecting the host

  • Age
  • Sex
  • Race
  • Habits, Customs, and religions
  • Exposure to agent
  • Defense mechanism of the host
• Immunity- protecting himself from infectious agent/pathogen
• Factors affecting immunity

  • Age
  • Sex
  • Race
  • Habits, Customs and religions
  • Exposure to agent
  • Defense mechanism of the host
• Immunity


  • Property of an individual to protect themselves from an infectious agent
  • Two types: Naturally acquired active immunity, Artificially acquired active immunity, Naturally acquired passive immunity, Artificially acquired passive immunity
• Active immunity


  • Antigen and the body makes the antibody
• Passive immunity


  • Antibodies that provide immediate protection against microorganisms
• Types of immunity

  • Active
  • Passive
• Non-specific resistance


  • Present at the time of birth or developed during maturation
• Specific resistance


  • Acquired as a result of prior exposure to a foreign substance
• Environmental factors of disease

  • Physical Environment
  • Climate
  • Geography and Location
  • Biologic Environment
  • Socio-Economic Environment
• The occurrence of disease follows biological laws which apply to both communicable and non-communicable diseases
• Disease results from an imbalance between the forces of the agent and host
• Incubation Period


  • Time between exposure to infectious agent up to the time of appearance of the earliest signs and symptoms
  • Two types: Clinical incubation period, Biological Incubation Period
• Categories of Isolation

  • Strict isolation
  • Contact isolation
  • Respiratory isolation
  • Tuberculosis isolation (AFB isolation)
  • Enteric Precautions
  • Drainage/secretion Precautions
  • Blood/body fluid Precautions
• Categories of Quarantine


  • Absolute or Complete Quarantine-The limitation of freedom of movement of those exposed to a communicable disease for a period of time not longer than the longest usual incubation period of that disease, in such manner as to prevent effective contact with those not so exposed.
  • Modified Quarantine- selective or partial limitation of movement, based on known differences in susceptibility.
• The natural history of diseases comprises the body of knowledge about the agent, host, and environmental factors relating to the disease process
• The process of infection involves six requirements for the successful invasion of the host by an infectious agent